Machine tool holders are used to interface the rotating spindle of a boring or milling machine to a cutting tool that will be used to machine or cut a workpiece. The cutting tool is securely mounted to the tool holder which is then drawn or pulled tightly into the spindle of the machine so as to rigidly maintain the cutting tool within the tool holder and the machine.
Recently, heat shrink tool holders have gained popularity in high tolerance machining applications for their ability to mount a cutting tool concentrically within the tool holder. In such tool holders, there is provided a central aperture sized slightly smaller than the diameter of the shank of the cutting tool to be used on the milling or grinding machine. The cutting tool is only insertable into the central aperture when the tool holder has been heated to the temperature necessary to thermally expand the tool holder and consequently the central aperture to a size which can accept the cutting tool shank. Subsequent to the insertion of the shank thereinto, the tool holder is allowed to cool to ambient temperature, thereby decreasing the size of the diameter of the central aperture. The thermal contraction of the tool holder and therefore the aperture creates a metal to metal press fit between the cutting tool and tool holder to thereby rigidly secure the cutting tool to the tool holder.
Additionally, machine tool extensions have been formed with heat shrink fittings such that cutting tools are secured to the machine tool extension by the heat shrink process. Such extensions are typically formed with a bore extending axially within one end, with the opposite end of the extension being insertable into the tool holder of a milling or boring machine. Similar to the central aperture of the heat shrink tool holder, the bore of the extension is sized slightly smaller than the shank diameter of the cutting tool. Therefore, the cutting tool shank is only insertable into the bore when the machine tool extension is heated to a temperature sufficient to thermally expand the bore to a size which can accept the cutting tool shank. Subsequent to the insertion of the shank into the bore, the cooling of the extension and the resultant thermal contraction of the bore creates a metal to metal press fit between the extension and the cutting tool, thereby rigidly securing the cutting tool to the extension.
However, while the heat shrink tool holder or extension is cooling to ambient temperature, it cannot be used for machining operations because the cutting tool is not rigidly secured to the tool holder. Therefore, after inserting the tool into the heated tool holder, the tool holder must be allowed to cool to ambient temperature in order to provide the strongest union between the cutting tool and tool holder. Only when the tool holder has cooled to ambient temperature can it be used for machining operations. Previous devices to cool tool holders and extensions have included chillers which can rapidly cool the tool holder or extension. However, such chillers are expensive to maintain and operate and are complex pieces of machinery which require special care to operate. Additionally, chillers are not environmentally friendly due to the coolants used therein and the possibility of leakage. Thus, there exists a need in the art for a heat shrink tool holder cooler that can cool heat shrink tool holders in an inexpensive and easy to maintain unit.
The present invention addresses the deficiencies in prior art coolers by providing a cooler that uses a blower to propel ambient temperature air over the heated tool holders to therefore cool the tool holders by a convection method. Therefore, the present invention provides an easy to maintain and inexpensive unit to quickly cool heat shrink tool holders or extensions to ambient temperature.